The present invention relates to information transmission along railroad tracks. Conventional communication along railroad tracks between stations or between trains and stations involves conventional radio frequency transmission or sophisticated satellite communications. Each of these systems require command centers, repeaters and other signal enhancing devices to provide uninterrupted information. Conventional radio transmission has inherent difficulties resulting from not only environmental interference and blackout, but also loss of communication with trains while passing through tunnels or certain terrains.
Prior attempts to utilize the features of railroad tracks for generating information or for communicating between sections involved the application of electricity in either pulsed or modulated form wherein the information of the signal was transmitted as a function of relay systems placed at intervals along the track or is a function of interruptions of constant signals along the track which needed to be monitored at short intervals.
U.S. Pat. No. 1,517,549 uses an electrical high frequency signal because it eliminated information concerning trains that were much further ahead and not considered a danger. This high frequency limited the signal because of high attenuation characteristics.
U.S. Pat. No. 3,715,669 to LaForest used a receiver for a frequency modulated overlay track circuit wherein components such as relay capacitors and resistors were connected to the rail and its operation depended upon the wheels of the train interrupting an electrically generated signal through the track by use of a shunt which blocks signals to the transmitter.
The U.S. Pat. No. 3,949,959 to Rhoton and U.S. Pat. No. 3,984,073 to Wood et al. concern antenna apparatus for coupling audio frequency signals related to one or the other of vehicle track rails. Voltage is injected into the vehicle track rails. This system is related to the detection of sound waves.
U.S. Pat. No. 4,369,942 to Wilson is a signal communication system which uses an electrically generated current including insulated tracks to engage a rail crossing signal wave system. Low voltage current initiates or induces the signal.
Other forms of proposed communication include the utilization of a wave guide principle wherein the track bed and the bottom of a moving train acted as a xe2x80x9cwave guidexe2x80x9d in the reference to Myers, U.S. Pat. No. 4,207,569.
Another form of transmission included the use of a transponder system by Birken in U.S. Pat. No. 4,932,614 wherein a rail current was set up in order to complete a loop through a shunt or a short circuit at the end of a track segment.
The U.S. Pat. No. 4,442,988 to Laurent et al. passes information through rails by using transmission zones with a resonant circuit tuned to a carrier frequency of signals emitted by a conductive loop placed between two rails of the track at the end of each block or zone. This system uses a continuous wave transmission in order to detect information rather than communicate information from one position to another.
These systems have the disadvantage that they are only able to be used over short distances or that they depend on interruptions in signal to generate information or that the signal itself represents the information which is subjected then to attenuation and noise related problems when substantial distances of track are involved.
The present invention overcomes prior art problems by providing an improved method and apparatus for transmitting and receiving information or general communication, including but not limited to location, speed and direction of rail traffic, to operators, and other personnel.
It is an object of the present invention to allow for transmission and or reception of information utilizing the existing rail system as both the transmission and reception medium for a variety of signals including radio frequency, acoustic, and lightwave systems.
The present invention accomplishes its objective by using conventional railroad steel tracks which are mounted on railroad ties. These rails are electrically coupled to each successive length of track by conductive cable or a solid weld. Railroad equipment traverses the rails using a flanged steel wheel which rolls on top of the steel rail. The present invention provides for transmission and reception of signals directly into the rail through a suitable tuned inductor or through the wheel into the rail. The transmitted signals are received from the rail back through the wheel, or tuned inductor, or other suitable conductive media to the equipment. Additionally, a variety of electromagnetic induction or conduction devices may be utilized in the vicinity of the track. Current federal regulations prohibit any part of the equipment mounted on a train, other than the wheel, from being any closer to the rail then 2.5 in. (6.35 cm).
It is another object of the present invention to avoid any noncompliance with the FCC (Federal Communications Commission) regulations prohibiting radio and other frequency interference, while also providing a reliable unbroken communication when transmitting information through and around natural and man-made structures.
It is a further object of the present invention to provide a system, using the railroad tracks, which transmits a signal to trains or equipment operators or dispatchers or other regional or national traffic control personnel, and which allows users to determine the proximity of such equipment, including the speed, track, location and direction of travel.
An additional beneficial aspect of the present invention is its ability to detect anomalies, defects, or discontinuities in the track itself. This is accomplished by virtue of the transmission and reception of signals through the rail. Such signals or reflected signals would necessarily be altered by anomalies, defects, or discontinuities in way such that they could be compared to a database of recorded anomalies derived from tests or samples taken from sections of track with known existing defects, or compared with a range of conditions considered to be normal in existing rail systems, or compared to both.
The objects of the present invention are accomplished by a method of transmitting information through a railroad track or other electrically conductive rail equipment,(e.g. trainline or cantenary) which involves an introduction of a signal containing information at a first location on the track or conductor and the detection of the signal which contains the information transmitted through the rail or other conductor to a second distant location. Subsequently, the information is extracted from the detected signal.
The objects of the present invention are further achieved by an apparatus which transmits information through the railroad track using a signal source which outputs an information encoded signal into either one or both of the rails of a track. A remotely positioned receiver detects the encoded signal transmitted through the track and then extracts the information from the signal.
It is a further object of the present invention to provide a method for transmitting information by the introduction into the rail, at a first location, of a radio frequency signal containing the information and subsequently detecting the signal at a second location, which is remote from the position where the signal was introduced into the track. The information is then extracted from the transmitted radio frequency signal and analyzed. It is a further object of the invention to provide a method of transmitting information through a railroad track by introducing an acoustic signal containing the information into the railroad track at a first position. At a remote position, the acoustic signal which was transmitted through the railroad track is detected and the information is extracted from the transmitted acoustic signal and then processed.
According to yet another method of the present invention, specific information, transmitted as a specific, universally known form of signal along a railroad track, is received by detecting a plurality of audible signals at a position which is remote from the source of the specific audible signal. Subsequently, the detected plurality of signals are analyzed and the specific audible signal is isolated. The specific audible signal is then processed to provide the specific information.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.